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    Track tire pressure - need input!

    Folks,

    I've started tracking my 07' 997TT and am enjoying the learning curve. However I am finding that tire pressure is a more important consideration than with my previous track cars. Some experienced instructors (and I asked 4) informed me that I should keep my PSI (hot tire pressure) at about 42 for the rears and 40 for the fronts to add grip to the rear end. This seems to reduce rear end shifting but it also gives me a low or flat tire warning. I do a few laps and the tires heat up to about 45 but the computer reads about 5 PSI lower and gives me this warning. I'm running the stock Michelin Sport tires.

    So, can someone help me with this?
    (1) Is there a problem with the computer reading about 5 PSI (or more ) lower and if so can the dealer correct this? They seemed disinterested in this when I brought to their attention and couldn't agree up whether the computer or manual tire gauge (I have some good ones) was the "correct reading."
    (2) What tire pressure are you folks using on the track and are you going by tire pressure gauge or computer?

    Thanks, I sure could use some help with this.
    C.

    Re: Track tire pressure - need input!

    Track tire pressures depend on the tire used. Pilot Cups are best at 30 hot - meaning you will start out in the 20's cold. 45 hot on PS2's may be too high still. Best way to know is to check with a contact pyrometer and bleed air until the temps are even across the tread. Disregard the TPMS sensors on the track

    Re: Track tire pressure - need input!

    Quote:
    Camus said:
    Folks,

    I've started tracking my 07' 997TT and am enjoying the learning curve. However I am finding that tire pressure is a more important consideration than with my previous track cars. Some experienced instructors (and I asked 4) informed me that I should keep my PSI (hot tire pressure) at about 42 for the rears and 40 for the fronts to add grip to the rear end. This seems to reduce rear end shifting but it also gives me a low or flat tire warning. I do a few laps and the tires heat up to about 45 but the computer reads about 5 PSI lower and gives me this warning. I'm running the stock Michelin Sport tires.

    So, can someone help me with this?
    (1) Is there a problem with the computer reading about 5 PSI (or more ) lower and if so can the dealer correct this? They seemed disinterested in this when I brought to their attention and couldn't agree up whether the computer or manual tire gauge (I have some good ones) was the "correct reading."
    (2) What tire pressure are you folks using on the track and are you going by tire pressure gauge or computer?

    Thanks, I sure could use some help with this.
    C.



    you are too high at the rear and way way too high at the front. cold front pressures should be 33 and rear 39.
    TPMS should not be giving a low pressure warning at 40/42, something is wrong with your sensors/computer. Mine reads 2-3 below but does not warn until I am below 30 (real).

    Re: Track tire pressure - need input!

    Please note that I am referring to the HOT tire pressure when on the track (40/42 HOT). The instructors suggested having a bit lower psi on the rears to help reduce oversteer.

    You are right, and do run 33/39 around town but add about 10 psi on the track (from heat) and it seemed too much. My computer does seem to read about 5 psi low but the dealer doesn't seem to think this something to investigate.

    I appreciate the advice to use the computer for non-track driving and the manual tire gauge for the track.

    Anyone else experience the computer-tire gauge psi
    measurement difference?

    You'd think for $150K this would be a non-issue given the TT is built for all driving styles and interests.

    Safe driving folks!

    Re: Track tire pressure - need input!

    Oh oh, I'm replying to myself! No worries (?), just left it too late to edit my note. I just wanted to add, if it's necessary I'm not sure, that the MAX psi for the tires is 50, so recommended daily 39 (rear) cold psi + increased heat on the track could lead to a safety issue.

    Re: Track tire pressure - need input!

    Quote:
    Camus said:
    Oh oh, I'm replying to myself! No worries (?), just left it too late to edit my note. I just wanted to add, if it's necessary I'm not sure, that the MAX psi for the tires is 50, so recommended daily 39 (rear) cold psi + increased heat on the track could lead to a safety issue.



    You have to get a temp probe as eugene suggested to keep the temp readings uniform across the tread (regardless of the number itself) and this will require constant checking and lowering run after run. I tracked my car only once with the PS2s and they would overheat so much causing terrible understeer and oversteer both. I have since got hoosiers R6 for the occasional DE, they are cheaper and safer on the track. Street tires are not meant for the track and they get ruined very quickly.
    TPMS is the most idiotic feature of the TT and I wish I could get rid of it, it is never accurate and very annoying

    Re: Track tire pressure - need input!

    Thanks! I will look around and pick one up asap.

    Re: Track tire pressure - need input!

    I run mine at 32f/36r hot.

    Re: Track tire pressure - need input!

    I bet you too are getting a low or flat tire warning from the computer. But your lower hot psi levels encourage me to experiment further with lower track psi levels. Thanks!

     
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